TOXICITY ASSESSMENT OF BIOREMEDIATED CONTAMINATED DOMESTIC WATER SOURCES IN WESTERN NIGER-DELTA BY A PHYTOGENOTOXICTY TEST

Abstract

In this study, fungal mycelium was employed for the bioremoval of heavy metals in drinking water samples obtained from boreholes, streams and a pond in six rural communities in Warri North Local Government Area in Delta State. The efficacy of the fungal-based bioremediation technology for toxicity reduction in the contaminated water samples was evaluated using Allium cepa cyto-genotoxicity bioassay in vitro approach before and after treatment with the fungal biofilters. Data obtained from physicochemical analysis after a 24 h myco-filtration treatment of the water samples revealed significant (p < 0.05) reduction/total elimination of heavy metals and microbial load in the samples. Results obtained from the 96 hour macroscopic evaluation of A. cepa showed that, compared to onions grown in untreated samples, there was significant (p < 0.05) reduction in root growth inhibition in onion bulbs cultivated in mycofiltrated samples. Similarly, results obtained from cytological studies by the aceto-orcein squash technique in root tips of A. cepa grown in the contaminated water samples for 48 hours showed significant (p < 0.05) reduction in chromosomal aberrations. These findings indicate that the reduction in genotoxicity established by the Allium bioassay is highly correlated with myco-filtration bioremediation of the contaminated drinking water sources.